SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'b340ad58146485260816c64d124c103af97e18c38145b7d6a70934d266858ae4' 
  AND token = 'lpkTeZh1gYTQ4ArYJSehDhNjudaibz5qPs+lJ0i9qbk=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00040

JSON explain

{
  "query_block": {
    "select_id": 1,
    "message": "no matching row in const table"
  }
}